Block or noindex the tag and filter pages that create low-value crawl waste and duplication, which is most of them, while keeping the few that carry real search demand, and on a small site reframe the goal entirely, because the issue there is not crawl budget but index bloat and duplicate content. The decision splits on demand versus waste, page by page, rather than on a single blanket rule. Blocking every tag and filter page sacrifices the handful that actually earn traffic, and keeping them all floods your index with thin, overlapping URLs that compete with your real pages. Neither reflex is right.
The waste case covers the bulk of these pages. Most tag archives and filter combinations generate URLs that are near-duplicates of each other or of your main category and product pages, sliced and recombined in ways no one searches for. They add crawl load on large sites and index clutter on every site, and they offer searchers nothing a better page does not already provide. For these, noindex (often paired with letting them stay crawlable so the directive is seen, or disallowing the obvious infinite patterns) keeps them out of the way.
The demand case is the exception worth protecting. A small number of tags or filtered views map to real queries people actually type, like a filter for a specific size, color, or feature that has genuine search volume, or a tag that has become a coherent topic page in its own right. Those pages can rank and deserve to stay indexable. The test is whether anyone is searching for what the page represents, not whether the page exists.
On a small site, the budget framing is the wrong frame altogether. You almost certainly have no crawl-budget constraint, so blocking tag and filter pages will not free meaningful crawl capacity. What it does do, and the reason to still consider it, is control index bloat and duplication, keeping your index focused on the pages you want to compete with rather than diluted by dozens of thin variants.
So go through your tag and filter pages and keep the ones backed by real search demand indexable, then block or noindex the rest. Judge each by whether anyone searches for it, not by reflex, and on a small site do it to keep your index clean rather than to chase a budget you do not have.